1. Field of the Invention
This invention relates to providing electrical power to means for converting electrical power into ultrasonic frequency mechanical vibrations. While the invention has wide application, one use to which the invention is particularly suited is as a power supply to produce power for input to apparatus for ultrasonically mechanically vibrating a metal cutting tool as the tool cuts a workpiece.
2. Description of the Prior Art
Apparatus for delivering ultrasonic vibratory energy to a work-performing tool is disclosed in U.S. Pat. No. 3,640,180. Other patents relating to ultrasonic applications are U.S. Pat. Nos. 2,891,178; 2,891,180; 3,209,447; 3,283,182; and 3,466,970.
Ultrasonic vibration is commonly applied to metal-cutting tools to enhance the performance of the metal-cutting tools when mounted on metalworking machinery such as lathes. The machine operator may attempt manually to adjust tool vibrational frequency and/or tool vibrational amplitude if the operator observes that the cutting tool is excessively hot or that the cutting effect being achieved is not adequate. An excessively hot cutting tool will change color. Inadequate cutting effect is manifested as visible and/or audible slowdown of the metalworking machine.
Adjustment of cutting tool vibrational frequency and/or amplitude is a trial and error procedure. The machine operator may have data reflecting estimated tool loads for various types of cuts. This data may have been gathered by measuring power consumption of the lathe drive motor and correlating consumption with the type and quality of cut.
It is desirable to select both "mechanical" power input to the metalworking machine drive motor and ultrasonic power controlling vibrational amplitude of the cutting tool to provide the fastest, highest quality cut of the workpiece with minimal energy consumption. (As used herein, "mechanical" power denotes the power consumed by the metalworking machine drive motor.)
In general, a high degree of machine operator judgment is required to regulate machine operation and to regulate power input to the ultrasonic vibration means in which the cutting tool is mounted.
Typically, an operator will have recommended settings, based on past experience, for ultrasonic power and tool cutting speed (which defines power input to the machine) as a function of tool type, tool grade, cut geometry and type of cut, i.e. rough or finished. After consulting his handbook of recommended settings, the operator starts the machine, makes a cut and then may adjust the machine speed based on his observation of color of the cutting tool, color of metal chips removed by the tool and any discoloration of the workpiece occurring during cutting.
If the operator is utilizing ultrasonic vibration of the cutting tool, an additional judgement and adjustment may be required. If the cut is proceeding unsatisfactorily, the operator must evaluate whether there is too much or too little ultrasonic power and/or too much or too little mechanical power being input to the metalworking machine. Based on his experience and subjective judgment, the operator may adjust the speed of the motor of the metalworking apparatus or the cutting speed, both of which affect the mechanical power consumed during cutting, and/or may adjust the ultrasonic power input to the apparatus which ultrasonically vibrates the cutting tool.
Various applications of ultrasonic bonding and machining are disclosed in the article "Ultrasonics Produces Strong, Oxide-Free Welds" appearing in the May 1977 issue of Assembly Engineering, the article "Ultrasonic Welding--Its Principles, Requirements, and Uses" appearing in a recent issue of Assembly Engineering and in the Sonobond Corporation publications "Ultrasonically Assisted Machining of Aircraft Parts" dated November, 1979, "Ultrasonic Freestanding Armature Welder", "Ultrasonic Solid-State Bonding of Aircraft Structures" dated July, 1977, and "Ultrasonic Welding of Motor Armatures."